Pushbutton switch with improved guide means



April 1968 M. H ABRAMOWITZ 3,378,663

PUSHBUTTON SWITCH WITH IMPROVED GUIDE MEANS Filed March 10, 1966 I 34 INVENTOR. 32 MARK a ABRAM own-z 21;) 52 44 y Pugs; '7

ATT RNEY United States Patent 3,378,663 PUSI-IBUTTON SWITCH WITH IMPROVED GUIDE MEANS Marl; H. Abramowitz, Bergenfield, NJ., assignor to Lee Electric, Inc., West New York, NJ., a corporation of New Jersey Filed Mar. 10, 1966, Ser. No. 533,351 11 Claims. (Cl. 200-159) ABSTRACT OF THE DISCLOSURE The disclosed pushbutton switch has a housing sleeve with a button member supported in the sleeve for inward and outward movement, the button member having a nose with a cam surface normally projecting from one end of the sleeve and having a pair of diametrically opposed fins which extend from the nose along the inner surface of the sleeve and pass through a contact-supporting disc at the other end of the sleeve. Movable contacts are supported within the button member, the nose of which is urged outwardly of the sleeve by a compression spring. The fins guide the movement of the button member longitudinally within the sleeve and prevent turning or tilting of the button member when lateral forces are exerted upon the cam surface of the nose.

This invention relates to an improved pushbutton switch and more particularly to an improved switch of the type having a cam actuator button.

Switches having cam or bullet-nose actuator buttons are often employed to detect swinging, sliding, or turning movement. For example, such switches are employed in burglar alarm systems for detecting the movement of a transom, door, or window. In such applications the bullet-nose of the switch may translate a force exerted laterally of the nose to a force directed longitudinally of the nose, which is elfective to push the nose into a housing sleeve of the switch in order to actuate the switch contacts.

Switches available heretofore for such purposes have serious disadvantages, most notably their high cost, which have militated against their use. Mercury and magnetic switches are often used instead.

A typical bullet-nose switch of the prior art is made from expensive parts, many of which must be manufactured on a screw machine. Excessive, time-consuming, and expensive hand operations are required to assemble the parts. A metal bulletnose is threaded to a central metal guide pin which supports machined ring-shaped movable contacts and insulators. The guide pin passes through a central opening in an insulator disc supporting stationary contacts at the rear of the switch housing sleeve. In order to limit the outward movement of the bullet-nose, which is biased by a coil compression spring, the end of the guide pin external of the sleeve must be grooved and provided with a split retainer ring, which serves as a stop. The lateral pressure of the metal guide pin upon the insulator disc causes wear which eventually enlarges the disc opening enough to permit the bulletnose to tilt. This results in improper translation of the forces exerted upon the bullet-nose and jamming or other improper operation of the switch. Since the guide pin passes through the center of the switch, the stationary contacts must be spaced apart, so that it is difficult to obtain sufficient contact pressure and wiping action to ensure good electrical contact. The movable contacts have round cross-section and the stationary contacts have flat crosssection, so that only tangential engagement of the contacts is possible. The bullet-nose is free to turn about its ill Patented Apr. 16, 1968 axis, which may produce off-setting of the stationary contacts and further impair the electrical contact.

It is accordingly a principal object of the present invention to provide a pushbutton switch which overcomes the disadvantages of prior switches of the foregoing type.

More specifically, it is an object of the invention to provide a bullet-nose pushbut-ton switch that is inexpensive to manufacture, that provides long-term excellent electrical operation, that prevents turning or tilting of the actuator nose, that minimizes wear, and that is readily adapted to different types of eletcrical operation.

Briefly stated, but without intent to limit its scope, the switch of the invention comprises a housing sleeve with a button member supported in the sleeve for inward and outward movement. The button member has a nose, which normally projects from one end of the sleeve, and a pair of diametrically opposed fins which extend from the nose along the inner surface of the sleeve toward the other end, at which a disc supporting stationary contacts is mounted. The fins pass through openings at the periphery of the disc and prevent the button member from turning or tilting. The stationary contacts extend centrally into the sleeve and are resiliently self-biased toward each other. The button member is hollow and supports an insulator plate therein which lies along the axial plane of the housing sleeve and supports movable contacts adapted to fit between the stationary contacts. A coil compression spring supported in the sleeve between the fins exerts pressure upon elements of the plate to hold the plate in position in the nose and to urge the nose outwardly of the sleeve. The sleeve has an internal shoulder which engages an external shoulder of the button member to limit the outward movement.

The foregoing and other objects, advantages, and features of the invention, and the manner in which the same are accomplished will become more readily apparent upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings, which illustrate a preferred and exemplary embodiment, and wherein:

FIGURE 1 is a front end view of a switch of the invention showing the bullet-nose and a mounting flange head-on;

FIGURE 2 is a side view of the switch, showing the switch housing as well as the bullet-nose and the switch terminals;

FIGURE 3 is a longitudinal sectional view taken along line 3-3 of FIGURE 2 in the direction of the arrows;

FIGURE 4 is an orthogonal longitudinal sectional view taken along line 4-4 of FIGURE 5 in the direction of the arrows;

FIGURE 5 is a rear end view of the switch showing the terminals; and

FIGURE 6 is a fragmentary longitudinal sectional view taken along line 6-6 of FIGURE 5 in the direction of the arrows.

Referring to the drawings, a switch constructed in accordance with the invention comprises a cylindrical housing sleeve 10 with a button member 12. of circular crosssection supported in the sleeve for inward and outward movement. The button member has a bullet-shaped or cam actuator nose 14, which normally projects from one end of the sleeve, and a pair of diametrically opposed longitudinal fins 16 which extend from the nose along the inner surface of the sleeve toward the other end, at which an insulator disc 18 is mounted. The disc abuts the end of the sleeve and may be held in posit-ion by a pair of cars 20 (FIGURE 5) which are integral with the sleeve and are bent over the disc to retain it as shown. The disc 3 may have shallow peripheral notches to receive the ears and to position the disc positively.

The sleeve is provided with a transverse mounting flange 22 having screw holes 24. Typically, the sleeve and the mounting flange may be formed of brass, and the mounting flange may have an integral ring 26 over which the sleeve is pressed to join the sleeve and the flange. The inner end of the ring forms an annular shoulder 28, which serves as a stop, as will be described more fully hereinafter.

The button member 12 is preferably formed from one piece of insulating material, such as molded plastic. The insulator disc .18 is preferably formed of the same material and has diametrically opposed peripheral openings 30 (FIGURE through which the fins 16 pass with suflicient clearance to minimize wear of the edges of the openings but yet to prevent turning of the button member about its longitudinal axis. By making the fins and the insulator disc of the same type of material, wear of the edges of the openings in the disc is further reduced.

Principal guiding of the movement of the button member into and out of the housing sleeve results from the cooperation of the fins 16 with the inner surface of the sleeve, which is lightly engaged by the outer surface of the fins. The fins are preferably substantially rectangular in cross-section, the inner and outer surfaces of the fins being cylindrical. Because of the surface-to-surface contact of the fins and the housing sleeve over a substantial area, wear is minimized.

The insulator disc 18 supports a pair of planar stationary contacts 32, which extend longitudinally into the housing sleeve substantially centrally thereof. The base end of each contact may pass through a rectangular slot in the insulating disc and be bent over the outer surface of the disc into juxtaposition with an angulated terminal 34, which supports a terminal screw 36. The terminal may have a tip 38 (FIGURE 5) which protrudes into a small opening in the insulator disc to keep the terminal from turning about an eyelet or rivet 40, which passes through a hole in the disc and retains the terminal as well as the stationary contact 32. A strip of insulating material (or a thin insulating disc) may be placed over the inner end of the eyelet as shown at 42 in FIGURE 4 to prevent electrical contact of the eyelets with a coil compression spring 44 in the sleeve. Also, the eyelets may be filled with solder, if desired, to enhance electrical contact of the terminals and the contacts 32.

The inner ends 46 of contacts 32 are bent toward each other in a chevron configuration as shown in FIGURE 3. The contacts are formed of a suitable resilient metal, so that contact ends 46 are biased toward each other.

The button member 12 is hollow and has an internal annular shoulder 48 for supporting a pair of ears '50 (FIGURES 4 and 6) of an insulator plate 52. One end of the plate, adjacent to the ears, is curved as shown at '54, so that when the plate is inserted into the button member it becomes lightly wedged into the tapered recess 56 in the nose of the button member.

The coil spring 44 has one end against the insulator disc 18 and the other end between the plate 52 and the button member to engage the ears 50, thereby to retain the plate in position in the button member and at the same time to urge the button member outwardly of the housing sleeve. The button member has an external annular shoulder 58 which engages the internal annular shoulder 28 of the housing to serve as a stop and to limit the outward movement of the button member.

Plate 52 carriers planar conductive elements 60 constituting movable contacts which cooperate with the stationary contacts 32. The movable contacts are adapted to enter between the stationary contacts and to provide a substantial area of engagement with positive wiping pressure. As shown, the movable contacts may be constituted by a continuous strip of metal passing through a rectangular opening in the insulator plate 52 and bent into engagement with the sides of the plate. The movable contacts are doubly insulated from the sleeve by the insulation of the plate 52 and the button member. The insulator plate may pivot about the axis of the cars as the plate enters between the diverging ends 46 of the stationary contacts, thereby to render the movable contacts selfcentering and to ensure good electrical contact. All of the contacts may be inexpensive stampings.

If the ends 46 of the stationary contacts 32 actually touch, the switch will be normally closed. Conversely, if there is a space between the ends 46, the switch will be normally open. A normally closed switch may also be provided by making the length of the movable contacts sufiicient to enter between the ends 46 of the stationary contacts when the switch is at rest. Conversely, a normally open switch may be provided by having an insulating portion of plate 52 between the ends 46 of the stationary contacts when the switch is at rest. The electrical action of the switch depends upon the type of contact construction, and may be readily changed merely by substituting one type of plate 52 for another. The position and longitudinal extent of the conductive elements 60 upon the plate 52 may be selected to provide break, make, make and break, or break and make action when the bullet-nose is depressed.

From the foregoing description it is apparent that the switch of the invention is simple and inexpensive. The button member, previously assembled with the movable contact plate 52, may be inserted into the end of the housing opposite the flange 22. The spring 44 may be inserted, and then the insulator disc 18, previously assembled with the stationary contacts and the terminals, may be placed over the open end of the housing and retained as described above. Lateral or longitudinal pressure exerted upon the bullet-nose will operate the switch to provide the desired electrical switching action.

While a preferred embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that changes can be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims. Accordingly, the foregoing embodiment is to be considered illustrative, rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalents of the claims are to be included therein.

The invention claimed is:

1. A switch comprising a housing sleeve, a button member supported in said sleeve for inward and outward movement, said button member having a nose with a cam surface which normally projects from one end of said sleeve and a fin which is rigidly fixed to and extends from said nose along the inner surface of said sleeve in juxtaposition therewith toward the other end thereof, a disc mounted at said other end of said sleeve and supporting contact means which extends into said sleeve toward said button member, said button member having contact actuator means supported thereon which extends toward said contact means to cooperate therewith, a spring supported in said sleeve between said disc and said button member and urging said nose outwardly of said sleeve, and stop means for limiting the outward movement of said nose with respect to said sleeve, said disc having an opening adjacent to its periphery, said fin extending through said opening, said fin engaging said sleeve for guiding said button member for inward and outward movement relative to said sleeve and preventing substantial tilting of said button member when a force is exerted laterally on said cam surface of said nose.

2. The switch of claim 1, said button member having an additional fin spaced from the first-mentioned fin and extending from said nose along the inner surface of said sleeve toward said other end, said disc having an additional opening adjacent to its periphery, and said other fin extending through said additional opening.

3. The switch of claim 2, said fins having engaging said inner surface of said sleeve to be guided thereby and passing through said openings with clearance to minimize wear of the edge of said openings.

4. The switch of claim 2, said button member being formed of a single piece of plastic material with integral nose and fins, and said disc being of plastic material.

5. The switch of claim 1, said contact means com prising a pair of conductive contacts extending substantially centrally of said sleeve and biased toward each other, said contact actuator means comprising an insulator plate extending between said contacts.

The switch of claim 5, said button member being hollow and having an internal shoulder, said insulator plate having a pair of cars supported on said shoulder, said spring being a coil spring surrounding said contacts, having one end engaging said disc, and having its other end engaging said ears and urging the same toward said button member.

7. The switch of claim 6, said button member having a tapered recess and said plate being lightly wedged in said recess.

8. The switch of claim 5, said plate having planar conductive contact elements supported thereon and positioned to enter between said contacts, said contacts being planar and having diverging ends facing said contact elements.

9. The switch of claim 1, said stop means comprising an internal shoulder of said sleeve and an external shoulder of said button member.

10. The switch of claim 9, said sleeve having a mounting flange extending transversely thereof at said one end, said mounting flange having a ring extending into and joined with said sleeve and constituting said shoulder of said sleeve 11. The switch of claim 1, said sleeve being cylindrical and said button member having circular cross section, said button member having an additional fin diametrically opposed to the first-mentioned fin, said disc having an additional opening adjacent to its periphery with said additional fin extending through said opening, said fins having a cylindrical outer surface substantially entirely engaging the inner surface of said sleeve and passing through said openings with clearance.

References Cited UNITED STATES PATENTS 1,886,433 11/ 1932 Tregoning 200159 2,249,001 7/1941 Joost et al 200159 2,332,554 10/1943 Bolley 200159 FOREIGN PATENTS 24,009 1/ 1919 Denmark. 1,223,309 6/1960 France.

ROBERT K. SCI-IAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

